Sheet feeding mechanism

ABSTRACT

Sheet feeding mechanism for a printing or like machine, comprising a tape conveyor for feeding individual sheets successively to stops and a slow down device for preventing the sheets rebounding from the latter or impact therewith. Device comprises two pairs of feed rollers driven at a slower rotational speed than the linear speed of the tape conveyor, the sheets being fed through the nips of said pairs of rollers. One roller in each pair is arcuately gapped around part of its circumference so that each sheet is released by the rollers at an appropriate time.

United States Patent lnventor Charles flilllngdon Dickinson Burton Latimer, near Kettering, England Appl. No. 795,945 Filed Feb. 3, 1969 Patented Aug. 24, 1971 Assignee Tlmsons Limited Northamptonshire, England SHEET FEEDING MECHANISM 3 Claims, 4 Drawing Figs.

US. Cl 271/46 Int. Cl B6511 5/24 Field of Search 198/203; 271/46, 50

[56] References Cited UNITED STATES PATENTS 1,112,791 10/1914 Hardie 271/46 Primary ExaminerRichard E. Aegerter Attorney-Larson, Taylor & Hinds ABSTRACT: Sheet feeding mechanism for a printing or like machine, comprising a tape conveyor for feeding individual sheets successively to stops and a slow down device for preventing the sheets rebounding from the latter or impact therewith. Device comprises two pairs of feed rollers driven at a slower rotational speed than the linear speed of the tape conveyor, the sheets being fed through the nips of said pairs of rollers. One roller in each pair is arcuately gapped around part of its circumference so that each sheet is released by the rollers at an appropriate time.

PATENTED AUE24 I97! SHEET 2 [IF 2 super FEEDING MECHANISM This invention appertains to the control of individual sheets or sections which, after having been severed from a treated travelling web of relatively thin and flexible material, are required to be fed up to stops preparatory to the performance on the said sheets or sections of a subsequent operation.

In this regard, the invention is primarily applicable to the control of fed sheets or sections successively severed from a continuously travelling web of paper, thin card, film or the like which has been printed upon or/and perforated, punched or analogously treated. It is also primarily the intention that the individual treated sheets or sections shall, after having been fed up to the stops and whilst still located by the latter, be acted upon by a folding mechanism or device of any appropriate character. The invention is by no means limited in this respect, however, as it may be applied to any operation wherein sheets or sections require to be stopped.

The invention, moreover, is applicable exclusively to a sheet feeding mechanism of the kind in which sheets or sections are fed seriatim, e.g. from a cylinder, into a tape conveyor by means of which each sheet or section is in turn carried to the stops. A tape conveyor is one comprising cooperable top and bottom series of longitudinally extending endless tapes which are adapted to be driven at the samespeeds in respectively opposite directions. In such a conveyor, the top and bottom tapes are so relatively arranged that the lower runsof the top tapes and the upper runs of the bottom tapes are closely opposed parallel to one another and travel together in the same direction, the stops being disposed between the tapes at the relevant end of the conveyor. The'top and bottom tapes are passed around rollers some of which are appropriately driven, and each oncoming sheet or section as it is fed offthe -cylinder is guided between the opposed runs of the tapes.

As the running speeds of modern printing, perforating, punching and analogous machines progressively increase, the conveyance of individual sheets or sections to stops by a tape conveyor becomes commensurately more difficult. For instance, the leading edges of sheets or sections which are conveyed at too great a speed strike the stops too abruptly and so tend to rebound out of control or/and become damaged.

The object of the present invention is to provide, in a sheet feedingmechanism of the kind herein referred to, simple and efficient means for feeding sheets or sections successively severed from a travelling web to the stops at a suitably reduced speed.

That is to say, the aim is to provide means located within the confines of the tape conveyor for slowing down and exercising control over each cut sheet or section after it has been fed into sheet or section'at the stops and freed FIG. 3 is a further view similar to FIGS. 1 and 2, showing the from control of the feed rollers, and

FIG. 4 is a cross section taken on the line IV-IV of FIG. 2. Referring to the drawings, the tape conveyor comprises cooperable top and bottom series of endless tapes 1 and 2 respectively. These tapes are passed around rollers, such as those indicated at 3 and 4 and 5 and 6 at least two of which are appropriately driven so that the tapes are driven at the same speeds in opposite directions. The lower runs la of the top tapes 1 and the upper runs 2a of the bottom tapes are closely opposed and travel together in the same direction. The upper runs of the top tapes 1 are passed over a guide roller 7, whereas the lower runs of the bottom tapes 2 are passed over guide rollers 8 and 9. A roller 10 disposed above the lower runs la of the top tapes steadies these runs and helps to mainthe said conveyor and caused to move forwards at the speed of I the tapes but before it reaches the stops.

According to this invention, cooperable feed rollers, adapted to be driven at a rotational speed slower than the rectilinear speed of the cooperable runs of the tapes, are arranged with their nips in a plane extending between the tapes for gripping engagement with opposite sides of a sheet or section in the course of being conveyed by the tapes towards the stops, provision being made for the nips of the feed rollers to be relieved coincidentally with the arrival at the stops of the leading edge of the sheet or section.

In order that the invention may be more clearly understood and readily carried into practical effect, a specific example of the improved sheet feeding mechanism will now be described with reference to the accompanying diagrammatic drawings, wherein,

. FIG. 1 is side view of the tape conveyor, showing a sheet or section being fed towards the stops at the speed of the tapesthe cooperable feed rollers being inoperable,

FIG, 2 is a view similar to FIG. I but with the sheet or section shown gripped between the cooperable feed rollers and thus being fed at a speed slower than that of the tapes,

tain the close parallel relationship of the opposed runs 1a and 2a. The said runs 1a and 2a frictionally engage the upper and lower sides of the conveyed sheets or sections such as that indicated at S.

One of a plurality of spaced stops provided across and at right angles to. the path of the conveyed sheets or sections, at the relevant end of the sheet feeding mechanism, is'indicated at 11 in each of FIGS. 1, 2 and 3. Sheets or sections are fed seriatim from a cylinder 12 into the tape conveyor by means of which each sheet or section is in turn carried to the stops 11. The cylinder 12 is furnished with conventional grippers or the like (not shown) whereby successive sheets or sections are picked up and fed into the tape conveyor.

In accordance with the characteristic feature of the present invention, the illustrated sheet feeding mechanism is equipped with pairs of cooperable feed rollers 13,14 at least one roller of each such-pair being adapted to be rotationally driven at a speed slower than the rectilinear speed of the opposed runs 1a and 2a of the tapes. The nip'n of the feed rollers 13 and 14 of each pair (see FIG. 2) is in a plane extending between the tapes 1 and 2 for gripping engagement with opposite sides of a sheet or section S in the course of being conveyed by the tapes from the cylinder 12 towards the stops 1].

For most practical purposes there are only two coaxial pairs of the feed rollers l3, 14 these preferably being arranged, as shown in FIG. 4,.for gripping engagement with the longitudinal margins of a sheet or section S which project laterally beyond the outermost tapes of the tape conveyor. There are no limitations in these respects, however, as two pairs of feed rollers may, where space is available, be disposed at any appropriatelocations at the inner sides of the outermost tapes it might be possible in some cases, and where it is advantageous so to do, to employ more than two pairs of feed rollers.

In any event, it is only necessary to drive one feed roller of each pair-although the relevant rollers of the two or more pairs must naturally be driven at the same rotational speed the desired amount slower than the rectilinear speed of the tapes. In the particular arrangement shown in FIG. 4, each of the upper feed rollers 13 of the two pairs l3, 14 is secured upon the inner end of a laterally extending, relatively short drive shaft 15. These shafts are mounted to rotate in antifriction bearings 16 fitted within brackets 17. To the outer end of each shaft 15 is secured a driving gear 18, the arrangement being such that the two rollers 13 are driven at the same speed, i.e. a constant speed slower than that of the tapes 1 and 2. The feed rollers 14 are located below, in cooperative relation, with, the rollers l3the two rollers l4 being secured upon opposite end portions of a common shaft 19. This shaft is mounted to rotate within further antifriction bearings 20 fitted within depending portions l7a of the brackets 17.

Alternatively, the feed rollers may be driven, through the medium of, say, cranks or eccentric gears, at a varying speed. For example, the feed roller drive means may be so constructed and arranged that at the time a severed sheet or section S enters the nips n of the rollers 13, 14 the latter are being driven more quickly than they are subsequently driven at the time the nips are relieved as aforesaid.

It is convenient at this point in the description to explain I relief of the nips n of the pairs of feed rollers each time the leading edge of a slowed down sheet or section S arrives at the stops 11 is essential to free the sheet or section from the control of the rollers and so prepare it for a subsequent operation thereon.

Preferably, and as shown more clearly in each of FIGS. 1-3, the driven feed roller 13 of each pair is arcuately gapped as at 13a around an appropriate extent of its circumference so that the nip n of the cooperable rollers is established and maintained for part only of each revolution, this nip being relieved (by the gap 13a between the rollers) for the remainder of the same revolution. In this case the establishment, maintenance and relief of the nips require to be correctly related to the movement and position of each successive sheet or section S. That is to say, at theinstant the feed rollers 13, 14 are required to grip and slow down an oncoming sheet or section the nips must be established, as shown in FIG. 2, whereas the moment the said sheet or section reaches the stops 11 the nips must be relieved as shown in FIG. 3. In the last mentioned figure an oncoming sheet or section is indicated at S.

In the illustrated arrangement, the upper feed roller 13 of each pair is the driven and arcuately gapped one and is of a substantially larger diameter than the lower roller 14.

lnstead of one of the rollers of each pair being arcuately gapped, provision of any suitable character may alternatively be made for effecting separation of the rollers to relieve the nip.

I claim:

1. A sheet feeding mechanism comprising: sheet stop means; tape conveyor means forcarrying individual sheets or sections of a relatively thin and flexible material in turn up to said stop means and comprising a pair of tapes defining a sheet conveying path along which said pair of tapes engage opposite sides of said sheet or section to convey same along said path to said stop means; sheet speed slowdown means comprising two coaxial pairs of cooperable feed rollers disposed on opposite sides of said sheet and arranged with their nips located for gripping sheet margins laterally outside of the sides of the conveyor tapes intermediate the ends of said sheet conveying path along which a conveyed sheet is in engagement with said tapes, said feed rollers being arranged with their nip in the path of said sheet or sections for gripping engagement with opposite sides thereof; means for driving said feed rollers at a rotational speed slower than the rectilinear speed of the tape conveyor; and means for relieving said nip coincidentally with lower roller and is arcuately gappe d around an appropriate extent of its circumference so that the nip of the cooperable rollers is established and maintained for part only of each revolution when the rollers are required to grip and slow down an oncoming sheet or section, this nip being relieved by the gap between the rollers for the remainder of the same revolution when the said sheet or section reaches said stop means. 

1. A sheet feeding mechanism comprising: sheet stop means; tape conveyor means for carrying individual sheets or sections of a relatively thin and flexible material in turn up to said stop means and comprising a pair of tapes defining a sheet conveying path along which said pair of tApes engage opposite sides of said sheet or section to convey same along said path to said stop means; sheet speed slowdown means comprising two coaxial pairs of cooperable feed rollers disposed on opposite sides of said sheet and arranged with their nips located for gripping sheet margins laterally outside of the sides of the conveyor tapes intermediate the ends of said sheet conveying path along which a conveyed sheet is in engagement with said tapes, said feed rollers being arranged with their nip in the path of said sheet or sections for gripping engagement with opposite sides thereof; means for driving said feed rollers at a rotational speed slower than the rectilinear speed of the tape conveyor; and means for relieving said nip coincidentally with the arrival of the leading edge of a sheet or section at said stop means.
 2. A sheet feeding mechanism according to claim 1 wherein said tape conveyor means comprises a single tape disposed on either side of said sheet conveying path.
 3. A mechanism according to claim 1 wherein the upper feed roller of each pair is driven, is of larger diameter than the lower roller and is arcuately gapped around an appropriate extent of its circumference so that the nip of the cooperable rollers is established and maintained for part only of each revolution when the rollers are required to grip and slow down an oncoming sheet or section, this nip being relieved by the gap between the rollers for the remainder of the same revolution when the said sheet or section reaches said stop means. 